1. Field of the Invention
The invention disclosed herein relates to exploration for oil and gas and, in particular, to improved methods and apparatus for providing antennae on exterior surface of drilling equipment.
2. Description of the Related Art
In the exploration for oil and gas, it is necessary to drill a borehole into the earth. While drilling of the borehole permits individuals and companies to evaluate sub-surface materials and to extract desired hydrocarbons, many problems are encountered. Once such problem is that of harsh environments down hole.
Many apparatus may be used for performing surveys of sub-surface materials while drilling the borehole. In general, such apparatus are referred to as providing a “logging while drilling” (LWD) or “measuring while drilling” (MWD) function.
On most present day logging while drilling tools, resistivity antenna(e) are created by placing wire loop antennae inside of deeply grooved channels cut into a body of a drillstring. The depth of the cut creates signal losses and unwanted stresses in the material (i.e., steel) of the drill collar. In order to improve signal strength, a very wide channel and/or ferrite materials are used. Unfortunately, this does not improve performance under mechanical stress or reduce complexity of the assembly.
Therefore, what are needed are methods and apparatus that provide for improved implementations of antenna(e) on drill string apparatus. Preferably, the methods and apparatus provide for minimal machining of drill apparatus, enhancements to mechanical strength and improved signal strength.